In front of a chalkboard for a discussion on exercise theory, Coach Greg Glassman suggests it’s possible certain muscles of the body can lift loads that can do damage to other parts of the body by compromising midline stability. To save us from ourselves, the body might short-circuit and fail before those loads severely injure an athlete.
For example, many people can lift one leg in an L-sit, but both legs fall to the floor when they attempt to raise the second limb. This phenomenon isn’t seen when one holds dumbbells away from the body at shoulder height. Most people can raise one arm and then the second without failing.
Coach Glassman has his own explanation for the phenomenon: “I suspect that there’s a built-in failure mechanism neurologically for this peripheral muscle tissue to prevent a midline collapse.”
In other words, the body may well be wired to prevent us from lifting loads that compromise midline stability and put us at risk of injury.
Additional reading: Three Important Ab Exercises by Greg Glassman, published May 1, 2003.